The safety of air travel during inclement winter weather has increased as procedures relating to safe cold weather operations have been implemented by airlines and methods for removing ice and preventing ice build up have improved. United States Federal Aviation Administration (FAA) regulations, as well as those of international regulatory authorities, clearly prohibit the take off of an aircraft when frost, ice, or snow is adhering to the aircraft's wings or other critical surfaces. Additionally, dispatch or take off of an aircraft is prohibited by the FAA when environmental conditions indicate a reasonable expectation that frost, ice, or snow may adhere to aircraft surfaces, unless there is in place an approved ground deicing and anti-icing program. An aircraft with frost, ice, and/or snow on its wings cannot operate aerodynamically and may be at risk for problems caused by increased drag and stall speed and uneven lift.
Ground crews and/or contractors are usually charged with carrying out the procedures required to remove frost, ice, and snow from aircraft surfaces and the procedures required to prevent the build up of these frozen contaminants on aircraft surfaces. Deicing and anti-icing procedures typically involve the application of liquids formulated to melt frozen water and to prevent it from re-forming on aircraft surfaces. In some situations, these fluids are heated to improve melting. The fluids used to deice runways are different from those used on aircraft surfaces, and the two types of fluids may not be compatible. Runway deicing fluids, moreover, both alone and in combination with aircraft surface deicing fluids, can damage aircraft surfaces on wings and tails as well as wheel brakes, electrical system connectors, and hydraulic system components. It is generally recommended that deicing fluids not be sprayed directly onto aircraft wheels or brake assemblies or landing gear structures.
The deicing of runways may effectively melt ice or snow. The melted ice and snow form slush, however, which can build up on aircraft wheels and landing gear, including landing gear doors, bays, and switches. To help mitigate this, it is recommended that slush, frost, ice, and snow be removed from areas where an aircraft's nose and main landing gear tires will be positioned when the aircraft is parked at a gate or parking location. It is also recommended that these contaminants be removed from the aircraft's wheels and landing gear structures prior to take off. The Association of European Airlines (AEA) recommends that the application of deicing fluid in the landing gear and wheel bay areas should be kept to a minimum, if used at all. The use of means other than fluid, such as mechanical removal, air blast, heat, and hot air are recommended by the AEA to remove accumulations of blown snow. Deposits of snow or slush that have bonded to landing gear and wheel bay surfaces can be removed with hot air or hot deicing fluids. The aforementioned procedures may effectively remove frozen water deposits, such as slush and the like, from wheels, landing gear, and wheel bays prior to departure from a gate or a deicing station. Since the use of anti-icing agents on these structures is generally prohibited, there is no guarantee that additional deposits will not be accumulated during taxi on a treated wet or slushy runway prior to take off. Air temperatures encountered by an aircraft after take off and during flight in winter weather are likely to be cold enough to freeze water and/or slush present on landing gear structures or in wheel bays.
The movement of an aircraft on the ground during taxi with motors designed to move the aircraft's wheels with minimal or no assistance from the aircraft's main engines has been proposed. In U.S. Pat. No. 7,445,178 to McCoskey et al and U.S. Pat. No. 7,226,018 to Sullivan, for example, systems able to move aircraft on the ground during taxi using wheel motors are described. U.S. Pat. Nos. 7,975,960 and 8,220,740 to Cox et al, owned in common with the present application, describe a nose wheel control apparatus capable of driving a taxiing aircraft independently on the ground. None of these patents or publications, however, describes using the wheel motors or systems disclosed therein to move aircraft on the ground in adverse cold weather environmental conditions or that these devices have any function in the presence of snow, ice, slush, or other frozen contaminants.
The use of aircraft wheel motors both to move an aircraft on the ground and to perform an additional function is suggested in U.S. Patent Application Publications Nos. US2008/0258014 to McCoskey et al and US2010/0252675 to Malkin et al. McCoskey et al describes the use of a motor/generator mounted on and operated by the rotation of an aircraft wheel to create electrical energy from kinetic energy and suggests recovering waste heat from kinetic landing and transferring the recovered heat away from the aircraft through a transmission grid to a remote airport location for reuse. Malkin et al suggests the use of an electric motor to propel an aircraft's wheels during taxi and then to drive a compressor when the aircraft is in flight. Neither of these publications, however, suggests that the wheel motors described therein are useful for other purposes or that they could be used during adverse cold weather conditions to maintain wheel or landing gear structures free from frozen contaminants either on the ground or during flight.
A need exists for a method for the inflight deicing of aircraft landing gears, wheel wells, and associated structures and maintaining these structures free from frozen water contaminants, including ice, snow, slush, and frost, that employs an existing aircraft onboard drive means also used to move the aircraft during taxi on the ground.